High-temperature sodium myristate grease containing n, n&#39;diphenyl para-phenylene diamine



Patented Dec. 22, 1953 HIGH-TEMPERATURE SODIUM MYRISTATE GREASE CONTAINING N,N'DIPHENYL PARA-PHENYLENE DIAMINE George W. Eckert, Glenham, N. Y., assignor to The Texas Company, New York, N. Y., a cor- ,poration of Delaware .No. Drawing. Application February. 16, 1951 Serial No. 211,446

' 4 Claims. i The present invention relates to sodiummyristate greases suitable for the high temperature lubrication of ball and roller bearings. More particularly it relates to sodium myristate greases having improved high temperature performance characteristics which are imparted by small amounts of N,N' diphenyl para-phenylene diamine which they contain.

It has been found. that sodium myristate,

greases have special properties which make them particularly-suitable for the lubrication of antifriction bearings at high temperatures. Besides possessing a dropping .pointin excessof 400 they are resistant to the action of water andprovide satisfactory lubrication with negligible change in texture and consistency even attemperatures above 300 F. However sodium. myristate greases exhibit a tendency toeventually break down through physical and chemical changes, such as phase separation, when they are employed for the lubrication of ball and roller bearings at high temperatures and at high rotative speeds for a substantial period of time. The antioxidants and other additives which have been employed in other known types of ball-and roller bearing greases are generally ineffective in extending the service life of these greases to the desired extent under the conditions of high temperature and high shear stress to which theyare subjected in this type of service.

The principal objectof this invention is to provide a grease of greatly extended service life for the high temperature lubrication of anti-friction bearings, Another object-is to provide a sodium myristate grease having a service lifein excess of l000-hours at 300 F.iuanti-friction'bearing lubrication.

In accordance with my invention a grease suitable for the lubrication of ball androller bearin s at high temperatures and at high rotative speeds for long periods of time .comprises an oleaginous base thickened to abuttery consistency with a fatty acid soap which comprisesa predominant amount of sodium myristate, and containing a small amount sufficient to improve the high temperature performance characteristics thereof of N,N' diphenyl para-phenylene diamine. I have found that such greases are markedly superior in high temperature properties both to greases'of very different composition and to greases of otherwise similar composition contaming-additives which have been proposed heretof'ore for improving oxidation resistance and other properties oflball androllerbearinggreases. In particular, the greases of my inventionlhave '2 exceptional .lubricating properties for the long time lubrication of anti-friction bearings at temperatures up to .300" andat rotative speedsof 10,000 RFP. M. and higher. I

The sodium myristate soap which is employed as the thickening agent may be prepared by saponifying a mixture of low molecular weight fatty acidscomprising at least and preferably at least by weight of myristic acid and/or the glycerides of such acids withcaustic soda or other suitable sodium compound, preferably employing a small excess of the alkali sufiicient to provide an excess of about 0.1 to about 1% of free alkali in the finished grease. The grease may suitably contain from about 15% to about 25% by'weight of this soap.

The N,N' diphenyl para-phenylene diamine may be'present in the grease in widely varying amounts depending upon the'magnitude of the effect desired. In general, a suitable range will be from about 0.5% to about 8%, and preferably from about 1% toabout 5%, by weight based'on the weight of the grease.

The oleagincus base may be any high boiling organic oil of lubricating characteristics, such as a mineral oil fraction obtained from a parafiinic, naphthcnic or mixed base crude by any of the usualrefining methods, an animal or vegetable oil such aslard oil, corn oil, castor oil, or the like, or a synthetic oil obtained by polymerization or chemical condensation reactions, "as well as mixtures of these. It may advantageously be a blend of distillate and residual lubricating oil fractions from a parafiin base crude,

In addition to ,the.N,N diphenyl para-phenylene diamine, other'additives may bepresent .in the grease such as extreme pressure agents, antioxidants, anticorrosives, and so forth, so far as no incompatibility exists between them and N,N' diphenyl para-'phenylene diamine.

The greases of my invention may be-prepared by any of the'conventional methods for'obtaiming greases of the buttery or short fiber type suitable for the lubrication of anti-friction "bearings. They are preferably prepared by the method described in'the copending application of 0?. Puryear and'M. D. Bray, Serial Number 130,588, filed December 1, 1949, now Patent No. 2,542,570, dated February 20, 1951. According to the method of said application, a commercial myristic acid is "saponified with a small exccssof'sodium hydroxidesolution in the presence of small amounts of. mineral oil and Water, the resulting soap base dehydrated at a temperature in the range 295- 1 3201F. andsufiicient mineral oil added .to obtain the desired consistency, the mineral oil addition being carried out in two stages so that a total amount of mineral oil equal to at least twice the weight of the fatty acids initially charged is added before the temperature of the mass is allowed to drop below 250 F.

Table 1 below gives high temperature performance test data obtained on a number of greases prepared according to the above-described meth- 0d and stabilized by various different types of compounds including N, N diphenyl paraphenylene diamine. The base oil employed in the preparation of these greases was a 1 to 3 blend of a solvent refined and clay treated paraffinic distil ate oil having an API gravity of 29.2", and SUS "cosity at 100 F. of 333 and a COC flash point of 435 and a solvent refined, clay and acid treated parailinic residual oil having an API gravity of 27.9", an SUS viscosity at 100 F. of 1724.7 and a COC flash point of 555 F. The myristic acid employed had a neutralization number of 240, a saponification number of 2 11 and a titer, C. of 41.8. The finished greases contained about 20% of the sodium soap prepared from this myristic acid and were sli htly alkaline with about 0.3% of free alkali, calculated as sodium hydroxide. The additives were added to the greases at the end of the manufacturing proc ess after the temperature had dropped below about 250 F. The N, N diphenyl paraphenylene diamine was added in the form of a slurry in a part of the residual base oil.

TABLE High temperature performance test Hours to Failure Additive 5% Diohenylamino." 3% Diphenylarni v+2% ditertiary bntyl phenol 1. 1% Triohenyl uanidino 1% p,o'-Diamino diohenvl methan 1% s-Diohenyletbylenediamine 1% Diethylenetriamine. 5% lsooropoxy dinlicnylamine 4% p-Phcnylenc diamine 1% d i-b-Naohthyl ophenylene d iamiue 5% di-b-Naohtliyl p-nhonylone diaminc. 2.5% N.N" Dichrn l p-uhenvlone diamine 5% N,N Diplicnyl p-phenylene diamiua The High Temperature Performance Test of the foregoing table is a test for determining the performance characteristics of greases in antifriction bearings at elevated temperatures and high rotative speeds. The test unit consists essentially of a steel spindle supported on ball bearings in an electrically heated housing and driven by an electric motor connected into an electric circuit containing a low amperage fuse 0.1 ampere below that required for full load running. The bearings are Norma-Hofimann ABEC No. 3 grade, and are mounted on the spindle approximately 5 inches apart, one bearing being the test bearing and the other an outboard guide hearing. A thrust load of 17.5 pounds is applied to the test bearing. The test consists of operating the test bearing for twenty-four hours at 10,000 E. P. M. and at a temperature 7 of 300 F. or at a temperature between 250 F. and 475 F. followed by a shutdown and cooling period of two hours, and repeating this cycle until the lubricant fails, which is indicated by rupture of the low amperage fuse in the motor circuit. In starting up the test, three grams of the test grease are charged to the test bearing and worked into and around the race and balls; the outboard bearing may be packed with any suitable grease. The bearings are next rotated both clockwise and counterclockwise for one minute each at 200 R. P. M. and assembled into the test unit. The heaters and the motor are then started and the test bearing brought up to the test temperature as rapidly as possible, which requires 1.0 to 1.25 hours for a temperature of 300 F., while the spindle is rotated at a speed of 10,000 E. P. M. After 24 hours of operation the heaters and motors are shut off for 2 hours, during which the temperature of the test bearing drops to a minimum of 120-130 F. The total ho of operation, excluding the two hour shutdown periods, to the failure point is recorded as the hours to failure. A grease giving satisfactory lubrication for 1000 hours at 300 F. under the conditions of this test is considered a very superior lubricant for the lubrication of anti-friction bearings at elevated temperatures and at high rotative speeds.

As shown by the table, a sodium myristate grease containing N,N diphenyl para-phenylene diamine gave satisfactory lubrication in 'enti-friction bearings for over one thousand hours at 300 F. in the High Temperature Performance Test described above. The effect obtained by adding N,N' diphenyl para-phenylene diamine to the sodium myristate grease was almost twice that obtained by any of the other compounds tested, which are usually considered to be eifective stabilizing agents for organic lubricating compositions, as well as combinations of such additives and also by closely analogous derivatives of phenylene diamine.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefor only such limitations should be imposed as are indicated in the appended claims.

I claim:

I. A ball and roller bearing grease capable of lubricating anti-friction bearings at high rotative speeds for long periods at a temperature of 300 F. containing as the essential constituents a major proportion of an oleaginous liquid lubricating base, about 15-25% by weight based on the grease of a sodium soap of a soap-forming fatty material containing at least 70% based on the fatty material of myristic acid, said soap thickening said lubricating base to a buttery grease-like consistency, and about 0.5-8% by weight based on the grease of ILN' diphenyl psra-phenylene diamine.

2. Claim 1 wherein the fatty material contains atleast of myristic acid.

3. A lubricating grease consisting essentially of the following ingredients in the approximate specified proportions:

Sodium myristatc 15-25%. N,N diphenyl para-phenylene diamine 1-5%. Excess NaOI-I 01-10%.

Lubricating oil comprising a blend of a paraninic distillate oil and a residual oil Remainder.

droxide.

GEORGE W. ECKERT. 5

Beferenees Cited in the file of this patent UNITED STATES PATENTS Number Name Date 10 Van Gundy et a1. Sept. 14, 1926 7 Number 6 Name Date Hilliker Jan. 29, 1935 Adams et a1 Jan. 21, 1941 Woods et a1 June 13, 1944 Woodward et a1 Feb. 20, 1945 Vincent Aug. 2'7, 1946 Puryear et a1 Feb. 20, 1951' 

1. A BALL AND ROLLER BEARING GREASE CAPABLE OF LUBRICATING ANTI-FRICTION BEARINGS AT HIGH ROTATIVE SPEEDS FOR LONGER PERIODS AT A TEMPERATURE OF 300* F. CONTAINING AS THE ESSENTIAL CONSTITUENTS A MAJOR PROPORTION OF AN OLEAGINOUS LIQUID LUBRICATING BASE, ABOUT 15-25% BY WEIGHT BASED ON THE GREASE OF A SODIUM SOAP OF A SOAP-FORMING FATTY MATERIAL CONTAINING AT LEAST 70% BASED ON THE FATTY MATERIAL OF MYRISTIC ACID, SAID SOAP THICKENING SAID LUBRICATING BASE TO A BUTTERY GREASE-LIKE CONSISTENCY, AND ABOUT 0.5-8% BY WEIGHT BASED ON THE GREASE OF N,N'' DIPHENYL PARA-PHENYLENE DIAMINE. 